refactor(compiler-dom): use faster sets in vOn

[CyberAP]

No description provided.

[yyx990803]

Turns out a benchmark shows that in check or plain object access is about 5x faster than using Sets, mostly because the objects are static so their property access is well-optimized by the engine. We probably want to refactor all existing usage of Set checks to just plain objects.

To save the redundant { key: true }, we probably need something like Vue 2's makeMap utility.

[CyberAP]

Turns out a benchmark shows that in check or plain object access is about 5x faster than using Sets, mostly because the objects are static so their property access is well-optimized by the engine. We probably want to refactor all existing usage of Set checks to just plain objects.

To save the redundant { key: true }, we probably need something like Vue 2's makeMap utility.

Got it. Would you mind sharing a benchmark? At least in Chrome I wan't able to confirm that (example test on jsperf).

[CyberAP]

Made the test comparing four methods for that check and yes, objects are faster.
https://jsperf.com/in-operator-vs-indexof-vs-set-has/1